Testing of packet/cell based data communication devices, such as asynchronous transfer mode (ATM) based network nodes, is becoming more important as data communication technologies mature. This is because the majority of data communications devices implement standard protocols, and thus their functionality is more or less equivalent. Hence, a distinguishing factor between such devices is their performance under known, real world conditions, which customers often examine in order to base their purchase decisions. The desire for performance testing requirements can be seen in the standards setting bodies and industry associations such as the International Telecommunications Union (ITU), the Internet Engineering Task Force (IETF) and the ATM Forum, where numerous performance testing specifications are currently in the process of being drafted.
Performance testing requires the use of standardized traffic patterns on all input ports to a data communication device so that different devices may be tested under the same traffic conditions. Unfortunately, the costs are enormous with the present practice of using a test generator for each port. The average per port cost of good ATM traffic pattern generator is quite high, so the cost to test a device having a large number of ports can be quite large. For example, some ATM switches have 92 ports thereby requiring 92 test generators at a cost of several millions of dollars in order to test the switch. Due to the large testing costs, customers do not test all ports at once and thus cannot obtain a true evaluation of the performance of a device for comparison against others.
Accordingly, there exists a need to carry out performance testing in data communication devices in a cost effective manner.